1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, the present invention relates to, for example, a semiconductor device, a display device, a light-emitting device, a power storage device, a driving method thereof, or a manufacturing method thereof. The present invention particularly relates to a semiconductor device, a display device, or a light-emitting device each including an oxide semiconductor, for example.
In this specification, a semiconductor device generally means a device which can function by utilizing semiconductor characteristics. For example, a semiconductor element such as a transistor; a power device; an integrated circuit, a power supply circuit, or a power supply converter circuit each including a power device; an electro-optical device; a semiconductor circuit; and an electronic appliance may be included in a semiconductor device or may include a semiconductor device.
2. Description of the Related Art
As a semiconductor device used for a power device, a power device manufactured with the use of silicon is widely prevalent. However, the performance of a power device including silicon is reaching its limit, and it is becoming difficult to achieve higher performance.
In the case where silicon is used for a power device, there is a limitation on operation at a high temperature because the band gap of silicon is small. Thus, in recent years, a power device including SiC or GaN, which has a wide band gap, has been developed.
The use of an oxide semiconductor in a semiconductor device which is used as a power device for a high-power application is disclosed (see Patent Documents 1 and 2).